This deep-field view of the sky (centre) taken by NASA’s Hubble and Spitzer space telescopes is dominated by galaxies – including some very faint, very distant ones – circled in red. The bottom right inset shows the light collected from one of those galaxies during a long-duration observation. Image credit: NASA/JPL-Caltech/ESA/Spitzer/P. Oesch/S. De Barros/I.LabbeNASA’s Spitzer Space Telescope has revealed that some of the Universe’s earliest galaxies were brighter than expected. The excess light is a byproduct of the galaxies releasing incredibly high amounts of ionising radiation. The finding offers clues to the cause of the Epoch of Reionisation, a major cosmic event that transformed the Universe from being mostly opaque to the brilliant starscape seen today.In a new study, researchers report on observations of some of the first galaxies to form in the Universe, less than one billion years after the Big Bang (or a little more than 13 billion years ago). The data show that in a few specific wavelengths of infrared light, the galaxies are considerably brighter than scientists anticipated. The study is the first to confirm this phenomenon for a large sampling of galaxies from this period, showing that these were not special cases of ...